Showing papers on "High dynamic range published in 1983"

Wide-band, noise-free, high-dynamic range dummy head with high fidelity reproduction of hearing stimuli

Abstract: This new dummy head recording system is being developed to prevent the transmission errors that frequently occur in head-type two-channel transmission equipment (inversion of direction, in-head localisation, elevation, sound colouration, lack of loudspeaker compatibility and perceptible internal noise). Its external geometry has been designed to take precise account of the acoustically effective directional parameters, which are structurally determined in human beings. It is equipped with two high quality calibratable microphones of the type normally used for measurement purposes, which produce an improvement in the electroacoustic transmission properties because of their small size, which permits a wide-band use of a simulation of the external ear as a passive acoustic amplifier and because of low internal noise and high dynamic range, and it ensures a frequency response of the microphone transfer functions comparable with that of a test microphone by using an active filter with free field sound radiation from the front, so that this system, on the one hand, provides a possibility of analysing sound stimuli by acoustical measurement techniques in the normal way and, in addition, with reproduction through a free-field-equalised earphone at the eardrums of a listening subject, generates the same sound pressure signals as if the subject was at the place of recording, and on the other hand, with reproduction through loudspeakers, no unwanted sound colouration occurs. The complete dummy head system is designed both for mains and for battery operation and is combined with an analog or digital recording instrument to form an autonomous recording and reproduction system.

An adaptive transversal filter

Abstract: A real time electronically programmable transversal filter with parallel architecture is described. The device is capable of operating at sampling rates in excess of 500KHz while maintaining high dynamic range. The device is built around an analog delay line designed using operational amplifiers and switching circuitry. Tap weight multiplication is performed using multiplying digital to analog convertors with 9 bit resolution. Results on a 16 stage prototype are described.

Signal generator for signal intensity display

Abstract: PURPOSE:To perform widely dynamic signal intensity display, by using an external control signal controlling an output of an amplifier in which the gain is stepwise changed, to a prescribed range, as a part of an intensity display signal of the signal inputted to the amplifier. CONSTITUTION:A variable gain amplifier 10 independent of a signal line of a tuner has five stages of gain such as 0, 20, 40, 60 and 80 dB by a control circuit 40. A signal representing the intensity is inputted to a window comparator 30 via said amplifier 10 and a detection circuit 20. The gain of the amplifier 10 is controlled so that the detected output G via the amplifier 10 is within a V1 and a V2 with the output of said comparator 30. The detected output G and gain controlling signals A-D from the control circuit 40 are added at an addition circuit 50 and displayed as the signal intensity in a meter 8. This signal is proportional to the logarithm of the input signal level, allowing to display the intensity of signal of high accuracy and high dynamic range.

A Simple Approach to High-Resolution Spectral Analysis

Abstract: A non-linear high-resolution technique for spectral analysis is presented. This technique differs significantly from those presently in use in that it operates on the system outputs rather than the input sampled data. The technique has general application and can be used wherever a response function is known or can be assumed. It has been applied to obtain the undersea ambient noise spatial spectrum from towed line array data and the frequency spectrum from time history data. The technique is relatively insensitive to errors and can handle data with high dynamic ranges as a result of its non-linearity. Examples of improved resolution in both space and frequency are given.